This invention relates generally to the development system in an electrophotographic printing machine, and more particularly, to the use of ultrasonics for toner charge and transport.
Single component xerographic development systems hold the promise of simpler and more reliable performance of lower cost than two component systems. Yet in comparison with two component systems, a single component system often falls short because the toner may have too low a charge level or too broad a distribution, making background control difficult. Also, some single component systems require magnetic toners for transport and applications in color are therefore limited. In addition, singe component systems often require conductive toner for charging and then have transfer problems and generally do not flow as well as two component developers.
It is known in the prior art to use sonic vibrations to facilitate the movement of particles along a sloping surface. For example, U.S. Pat. No. 3,637,115 discloses a sound transmitter to provide sound oscillations for vibrating a fixedly mounted diaphragm for sliding material down a sloping surface. It is also known to use a magnetically driven agitator to dispense particles. For example, U.S. Pat. No. 4,188,907 discloses an apparatus in which particles are dispensed from an open ended chamber. An oscillatory magnetic field vibrates a magnetic member at least partially immersed in the particles to prevent bridging and caking of the particles to facilitate the flow of the particles from the open end of the chamber. None of these references, however, are directed to the above mentioned problems in single component development systems. U.S. Pat. No. 4,546,722 discloses the use of a piezoelectric device on the inside of a developer sleeve at the nip of the developer station to propel toner toward an electrostatic latent image.
It would be desirable, therefore, to provide a development process that can use non-magnetic toners and where the charge levels will be higher and the distribution narrower than is commonly known. It would also be desirable to provide a development system that minimizes the need for moving parts and that provides improved flowability and eliminates the need for fluffing mechanisms in the system. Accordingly, it is an object of the present invention to improve single component development by providing an ultrasonic transducer for charging and transporting the toner. Further advantages of the present invention will become apparent as the following description proceeds and the features characterizing the invention will be pointed out with particularity and the claims annexed to and forming a part of this specification.